Electricity: measuring and testing – Of geophysical surface or subsurface in situ – Using electrode arrays – circuits – structure – or supports
Reexamination Certificate
2006-09-02
2009-08-25
LeDynh, Bot (Department: 2862)
Electricity: measuring and testing
Of geophysical surface or subsurface in situ
Using electrode arrays, circuits, structure, or supports
C324S370000
Reexamination Certificate
active
07579841
ABSTRACT:
Oil-based mud imaging systems and methods having standoff compensation. In some embodiments, disclosed logging systems include a logging tool in communication with surface computing facilities. The logging tool is provided with a sensor array having at least two voltage electrodes positioned between two current electrodes energized by an excitation source to create an oscillatory electric field in a borehole wall. The two current electrodes are each shielded with conductive shields to prevent current leakage into the logging tool body. A common mode voltage is measured, and the phase and amplitude of the excitation source is controlled to reduce the difference between the common mode voltage and reference voltage of a voltage detector. The logging tool is further provided with electronics coupled to the voltage detector and the current electrodes to determine a differential voltage between the voltage electrodes and two current flows from separate ones of the current electrodes. From the differential voltage and multiple current flows, the computing facilities determine borehole wall resistivity, and may display the resistivity as a borehole wall image.
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Dodge Carl
Monroe Myrick L.
Morys Marian L.
Pai Raj
Rosa Humberto E.
Halliburton Energy Service,s Inc.
LeDynh Bot
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